Ink set and recording method using the same

ABSTRACT

An ink set includes a reaction liquid containing coagulant; a first ink containing a color material; and a second ink containing a color material. The ink set is used for recording on a non-absorptive recording medium or a low-absorptive recording medium and for imparting the reaction liquid, the first ink, and the second ink to the recording medium in a superimposed manner in this order.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/964,829, filed Apr. 27, 2018, which is a continuation of U.S. patentapplication Ser. No. 14/327,724, filed Jul. 10, 2014, now U.S. Pat. No.9,982,153, issued May 29, 2018, which claims priority to Japanese PatentApplication No. 2013-171444, filed Aug. 21, 2013, Japanese PatentApplication No. 2013-182504, filed Sep. 3, 2013, and Japanese PatentApplication No. 2014-109749, filed May 28, 2014, the entire disclosuresof which are expressly incorporated by reference herein in theirentireties.

BACKGROUND 1. Technical Field

The present invention relates to an ink set and a recording method usingthe same.

2. Related Art

An ink jet recording method has been rapidly developed in many areas asit is possible to record a high definition image using a comparativelysimple device. For example, JP-A-2002-103783 discloses that recording isperformed on an OHP sheet for ink jet printing using an ink compositioncontaining titanium dioxide sol and a reaction liquid containingmagnesium sulfate to form an image, for example, to realize formation ofa white image having ink ejecting characteristics or high concealmentwhen forming the white image through the ink jet recording method.

However, there is a problem in that bleeding of a color ink occurs whena color image is recorded on the white image using the color ink if therecording is performed on a non-absorptive recording medium or alow-absorptive recording medium using the ink jet recording methoddisclosed in JP-A-2002-103783.

In addition, a method of heating the recording medium can also beconsidered instead of using the reaction liquid to suppress thebleeding. However, there is a problem in that high energy for heating isrequired and clogging occurs if the recording medium is heated withoutusing the reaction liquid.

SUMMARY

An advantage of some aspects of the invention is to provide an ink setin which it is possible to prevent bleeding among the inks and in whichthe clogging hardly occurs when a plurality of inks are recorded on anon-absorptive recording medium or a low-absorptive recording medium ina superimposed manner.

The present inventors have conducted extensive studies. As a result, thepresent inventors have completed an ink set including a predeterminedliquid for pretreatment separately from the plurality of ink withrespect to the non-absorptive recording medium or the low-absorptiverecording medium.

That is, the invention is as follows.

[1] According to an aspect of the invention, there is provided an inkset including a reaction liquid containing coagulant; a first inkcontaining a color material; and a second ink containing a colormaterial. The ink set is used for recording on a non-absorptiverecording medium or a low-absorptive recording medium and for impartingthe reaction liquid, the first ink, and the second ink to the recordingmedium in a superimposed manner in this order.

[2] In the ink set according to the above [1], at least any one of thefirst ink and the second ink may be a color ink containing a colormaterial or a black ink containing a black color material.

[3] In the ink set according to the above [2], the other one of thefirst ink and the second ink may be a white ink containing a white colormaterial or a metallic ink containing a metallic color material.

[4] In the ink set according to any one of the above [1] to [3], thecoagulant may contain at least one selected from a group consisting of apolyvalent metal salt and an organic acid.

[5] In the ink set according to above [4], the ratio of the number ofmoles (unit: mol) of the polyvalent metal salt contained in the reactionliquid to the total mass (unit: g) of the color material contained inthe first ink and the second ink may be 1000:1 to 31000:1 (the colormaterial: the polyvalent metal salt).

[6] In the ink set according to above [4] or [5], the ratio of thenumber of moles (unit: mol) of the organic acid contained in thereaction liquid to the total mass (unit: g) of the color materialcontained in the first ink and the second ink may be 800:1 to 5500:1(the color material: the organic acid).

[7] In the ink set according to any one of the above [1] to [6], thefirst ink may be the white ink containing the white color material orthe metallic ink containing the metallic color material and the secondink may be the color ink containing the color material or the black inkcontaining the black color material.

[8] In the ink set according to any one of the above [1] to [7], asurface tension of the reaction liquid may be less than or equal to 55mN/N at a temperature of 25° C.

[9] In the ink set according to any one of the above [1] to [8], thereaction liquid may further contain at least one selected from a groupconsisting of a component which becomes a receiving layer of an inkapplied after the reaction liquid, and a cationic resin.

[10] In the ink set according to the above [9], the mass ratio of atleast one (unit: g) selected from the group consisting of the componentwhich becomes the receiving layer, and the cationic resin, which arecontained in the reaction liquid, to the color material (unit: g)contained in the first ink may be 7:1 to 70:1 (the color material: atleast one selected from the group).

[11] According to another aspect of the invention, there is provided arecording method using the ink set according to any one of the above [1]to [10], the method including imparting a reaction liquid contained inthe ink set to a non-absorptive recording medium or a low-absorptiverecording medium; imparting a first ink contained in the ink set to thearea to which the reaction liquid is imparted; and imparting a secondink contained in the ink set to the area to which the first ink isimparted.

[12] In the recording method according to the above [11], after theimparting of the first ink and before the imparting of the second ink,the volatilization amount of a volatile component contained in thereaction liquid and the first ink on the non-absorptive recording mediumor the low-absorptive recording medium may be less than or equal to 95mass % with respect to 100 total mass % of a volatile component of thereaction liquid and the first ink before the imparting.

[13] In the recording method according to the above [11] or [12], theratio of the number of moles (unit: mol) of a polyvalent metal saltcontained in the reaction liquid per unit area of the non-absorptiverecording medium or the low-absorptive recording medium, to the totalmass (unit: g) of a color material contained in the first ink and thesecond ink may be 1000:1 to 31000:1 (the color material: the polyvalentmetal salt).

[14] In the recording method according to the above [1] to [13], theratio of the number of moles (unit: mol) of an organic acid contained inthe reaction liquid per unit area of the non-absorptive recording mediumor the low-absorptive recording medium, to the total mass (unit: g) ofthe color material contained in the first ink and the second ink may be800:1 to 5500:1 (the color material: the organic acid).

[15] In the recording method according to the above [11] to [14], theratio of the mass (unit: g) of at least one selected from a groupconsisting of a component which becomes a receiving layer of the firstink and the second ink, and a cationic resin, which are contained in thereaction liquid per unit area of the non-absorptive recording medium orthe low-absorptive recording medium, to the mass (unit: g) of the colormaterial contained in the first ink may be 7:1 to 70:1 (the colormaterial: at least one selected from the group).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIGURE is a side view schematically showing an example of a whole inkjet recording apparatus that can be used in the present embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, an embodiment of the invention (hereinafter, referred to as“present embodiment”) will be described in detail with reference to thedrawings as necessary, but the invention is not limited thereto. Variousmodifications can be made within the scope not departing from the gistthereof. The same elements are given the same reference numerals and thedescription will not be repeated. In addition, the positional relationsuch as top, bottom, left, and right is based on the positional relationshown in the drawing unless otherwise specified. Furthermore, the ratioof the dimension is not limited to the ratio shown in the drawing.

Ink Set

The ink set according to the present embodiment includes a reactionliquid containing coagulant; a first ink containing a color material;and a second ink containing a color material. The ink set is used forrecording on a non-absorptive recording medium or a low-absorptiverecording medium (hereinafter, also collectively referred to as“recording medium”) and for imparting the reaction liquid, the firstink, and the second ink to the non-absorptive recording medium or thelow-absorptive recording medium in a superimposed manner in this order.Hereinafter, the first ink and the second ink are also simply andcollectively referred to as “ink”.

Reaction Liquid

The reaction liquid contains the coagulant. By using such reactionliquid, it is possible to obtain a recorded matter with good qualitywithout heating the recording medium and to suppress clogging of anozzle caused by the nozzle being dried or the like due to the heatingof the recording medium. Specifically, with the inclusion of thecoagulant, it is possible to coagulate a pigment contained in the firstink or a pigment contained in the second ink without heating. Thus, itis possible to prevent bleeding of the second ink and unevenness of thefirst ink, thereby obtaining the recorded matter with good quality.

Coagulant

The coagulant is not particularly limited, but it is preferable that thecoagulant contain at least one selected from a group consisting of apolyvalent metal salt and an organic acid, for example.

Polyvalent Metal Salt

The polyvalent metal salt is not particularly limited, but for example,a polyvalent metal salt of an inorganic acid or a polyvalent metal saltof an organic acid is preferable. Such a polyvalent metal salt is notparticularly limited, but examples thereof include a salt of alkalineearth metal (for example, magnesium and calcium) of a group 2 in theperiodic table; a salt of transition metal (for example, lanthanum) of agroup 3 in the periodic table; a salt of earth metal of a group 13 inthe periodic table (for example, aluminum); and a salt of lanthanides(for example, neodymium). Carboxylate (formic acid, acetic acid,benzoate, or the like), sulfate, nitrate, chloride, and thiocyanate aresuitable as these polyvalent metal salts. Among these, a calcium salt ora magnesium salt of carboxylate (formic acid, acetic acid, benzoate, orthe like); a calcium salt or a magnesium salt of sulfate; a calcium saltor a magnesium salt of nitrate; calcium chloride; magnesium chloride;and a calcium salt or a magnesium salt of thiocyanate are preferable.The above-described polyvalent metal and the salt constituting thepolyvalent metal salt may be a combination of the above and may be ahydrate. The polyvalent metal salt may be used alone or in a combinationof two or more thereof.

The content of the polyvalent metal salt with respect to a total 100mass % of the reaction liquid is preferably 0.5 mass % to 5 mass %, morepreferably 0.5 mass % to 4 mass %, and still more preferably 1 mass % to4 mass %. By setting the content of the polyvalent metal salt to bewithin the above-described range, the obtained recorded matter tends tobe more excellent in the bleeding resistance.

Organic Acid

The organic acid is not particularly limited, but examples thereofinclude phosphoric acid, oxalic acid, malonic acid, succinic acid,citric acid, and acetic acid. Among these, at least a monovalentcarboxylic acid is preferable. With the inclusion of such carboxylicacid, the obtained recorded matter tends to be more excellent in thebleeding resistance. The organic acid may be used alone or in acombination of two or more thereof. In addition, the organic acid may bein a state of a salt. The organic acid salt is not particularly limited,but an example thereof includes the above-described salts of organicacids (where it is not overlapped to the above-described polyvalentmetal salt). The above-described salts of the organic acids are notparticularly limited, but an example thereof includes sodium acetate.The organic acid salt may be used alone or in a combination of two ormore thereof.

The content of the organic acid with respect to a total 100 mass % ofthe reaction liquid is preferably 1 mass % to 15 mass %, more preferably1 mass % to 14 mass %, and still more preferably 1 mass % to 7 mass %.By setting the content of the organic acid to be within theabove-described range, the obtained recorded matter tends to be moreexcellent in the bleeding resistance.

It is preferable that the reaction liquid further contains at least oneselected from a group consisting of a component (hereinafter, alsosimply referred to as “component of a receiving layer”) which becomes areceiving layer of at least one of the first ink and the second ink, anda cationic resin.

Component which Becomes Receiving Layer of at Least One of First Ink andSecond Ink

By allowing the reaction liquid to contain the component of thereceiving layer, the obtained recorded matter tends to be more excellentin the bleeding resistance and color developing property. The componentof the receiving layer is not particularly limited, but examples thereofinclude an inorganic fine particle or a solid fine particle including asolid resin fine particle in liquid. Examples of such particles includea cationic particle, a nonionic particle, and an anionic particle. Amongthese, particles where a gap remains between fine particles in a statewhere the particles are adhered to a recording medium to form a coatingfilm. The “gap” refers to a space in a state where the coating film ofthe reaction liquid is dried. When the reaction liquid is imparted tothe recording medium and the coating film is formed, it is possible tomake a gap between the fine particles in the coating film using thecomponent which becomes the receiving layer and at least an ink impartedafter the reaction liquid is absorbed in the gap. Therefore, thebleeding is further suppressed, which is more preferable. In general,the component which becomes the receiving layer is at least a componentwhich becomes a receiving layer of the first ink. Furthermore, thecomponent which becomes the receiving layer may be a receiving layer ofthe subsequently imparted second ink.

A particle with a cationic property exhibits an effect of forming alayer that receives the first ink or the second ink, and imparting acohesive property. The cationic particle is not particularly limited,but an example thereof includes SNOWTEX ST-AK (trade name, manufacturedby NISSAN CHEMICAL INDUSTRIES, LTD.).

A particle with an anionic property or a nonionic property forms a layerthat receives the first ink or the second ink. The anionic particle orthe nonionic particle is not particularly limited, but an examplethereof includes anionic colloidal silica. An example of the commonlyavailable anionic colloidal silica includes SNOWTEX ZL (trade name,manufactured by NISSAN CHEMICAL INDUSTRIES, LTD.).

The content of the component of the receiving layer with respect to atotal 100 mass % of the reaction liquid is preferably 0.1 mass % to 10mass %, and more preferably 0.1 mass % to 6 mass %. By setting thecontent of the component of the receiving layer to be within theabove-described range, the obtained recorded matter tends to be moreexcellent in the bleeding resistance and color developing property. Thecomponent of the receiving layer may be used alone or in a combinationof two or more thereof.

Cationic Resin

By allowing the reaction liquid to contain a cationic resin, theobtained recorded matter tends to be more excellent in the bleedingproperty and the color developing property. The cationic resin is notparticularly limited, but examples thereof include a resin which issoluble in the reaction liquid and a resin which shows a dispersionstate in liquid such as resin emulsion. The interaction between thecationic resin and the pigment contained in the first ink or the secondink is comparatively weak compared to the above-described coagulant, andtherefore, the cationic resin works as an auxiliary agent of thecoagulant rather than working as the coagulant. A resin which is solublein the reaction liquid is preferable in terms of excellent interaction.

The resin which is soluble in the reaction liquid is not particularlylimited, but an example thereof include an amine-based resin, andexamples of the amine-based resin include polyallylamine andpolyallylamine derivatives.

The resin emulsion is not particularly limited, but examples thereofinclude a polyolefin-based resin, a urethane-based resin, anacrylic-based resin, and a polyester-based resin. Another examplethereof includes resin emulsion that can be included in the ink to bedescribed later. A preferable example of commonly available resinemulsion includes Arobase CD-1200 (trade name, manufactured by UNITIKALTD., polyolefin-based resin).

The content of the cationic resin with respect to a total 100 mass % ofthe reaction liquid is preferably 0.1 mass % to 10 mass %, and morepreferably 0.1 mass % to 6 mass %. By setting the content of thecationic resin to be within the above-described range, the obtainedrecorded matter tends to be excellent in the bleeding resistance and thecolor developing property. The cationic resin may be used alone or in acombination of two or more thereof.

The reaction liquid can also contain a solvent, a surfactant, or thelike in addition to the above.

Solvent

It is preferable that the reaction liquid in the present embodimentfurther include a solvent. The solvent is not particularly limited, andfor example, an organic solvent or water can be used as the solvent.

Examples of water include water from which ionic impurities are removedas much as possible, for example, pure water or ultrapure water such asion-exchanged water, ultra-filtered water, reverse osmosis water, anddistilled water. In addition, use of water which is sterilized byirradiation with ultraviolet light, addition of hydrogen peroxide, orthe like can prevent generation of mold or bacteria during long-termpreservation of the reaction liquid. Accordingly, the storage stabilitytends to be further improved.

The content of the water with respect to total 100 parts by mass of thereaction liquid is preferably 80 parts by mass to 95 parts by mass, andmore preferably 85 parts by mass to 95 parts by mass. By setting therange of the content of the water to be within the above-describedrange, the viscosity tends to become low.

A volatile water-soluble organic solvent is more preferable as theorganic solvent. The organic solvent is not particularly limited, butspecific examples thereof include alcohols or glycols such as glycerin,ethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol,1,2-pentanediol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol,1,6-hexanediol, diethylene glycol mono-n-propyl ether, ethylene glycolmono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethyleneglycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether,diethylene glycol mono-n-butyl ether, triethylene glycol monobutylether, diethylene glycol mono-t-butyl ether, propylene glycol monomethylether, propylene glycol monoethyl ether, propylene glycol mono-t-butylether, propylene glycol mono-n-propyl ether, propylene glycolmono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropyleneglycol mono-n-butyl ether, dipropylene glycol mono-n-propyl ether,dipropylene glycol mono-iso-propyl ether, diethylene glycol dimethylether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether,diethylene glycol ethyl methyl ether, diethylene glycol butyl methylether, triethylene glycol dimethyl ether, tetraethylene glycol dimethylether, dipropylene glycol dimethyl ether, dipropylene glycol diethylether, tripropylene glycol dimethyl ether, methanol, ethanol, n-propylalcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol,iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol;N,N-dimethylformamide; N,N-dimethylacetamide; 2-pyrrolidone;N-methyl-2-pyrrolidone; 2-oxazolidone; 1,3-dimethyl-2-imidazolidinone;dimethyl sulfoxide; sulfolane; and 1,1,3,3-tetramethyl urea.

The organic solvent may be used alone or in a combination of two or morethereof. The content of the organic solvent is not particularly limitedand can be appropriately set as necessary. Among these, it is preferableto use one or more selected from a group consisting of 1,2-hexanediol,triethylene glycol monobutyl ether, and dipropylene glycol mono-propylether.

The content of the organic solvent with respect to a total 100 mass % ofthe reaction liquid is preferably 1 mass % to 10 mass %.

Surfactant

It is preferable that the reaction liquid used in the present embodimentcontain a surfactant. The surfactant is not particularly limited, butpreferable examples thereof include at least one selected from a groupconsisting of an acetylene glycol-based surfactant and apolysiloxane-based surfactant.

Among these, the polysiloxane-based surfactant is more preferable sinceits solubility to the reaction liquid becomes high and foreign materialsare hardly generated in the reaction liquid.

The above-described acetylene glycol-based surfactant is notparticularly limited, but preferable examples thereof include one ormore selected from 2,4,7,9-tetramethyl-5-decyne-4,7-diol and an alkyleneoxide adduct of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and2,4-dimethyl-5-decyne-4-ol and an alkylene oxide adduct of2,4-dimethyl-5-decyne-4-ol. These are commonly available products suchas an Olfine 104 series or an E series such as Olfine E1010 (trade name,manufactured by Air Products Japan, Inc.), and Olfine PD-002W, Surfynol465 or Surfynol 61 (trade name, manufactured by Nissin Chemical IndustryCo., Ltd.).

In addition, the polysiloxane-based surfactant is not particularlylimited, but examples thereof include BYK-347 and BYK-348 (BYK JapanKK).

The content of the above-described surfactant with respect to a total100 mass % of the reaction liquid is preferably 0.1 mass % to 3 mass %.

The surface tension of the reaction liquid is preferably less than orequal to 55 mN/N, and more preferably less than or equal to 40 mN/N at atemperature of 25° C. By setting the surface tension to be within theabove-described range, it is possible to uniformly coat the reactionliquid while performing the recording on the recording medium. Inaddition, the lower limit of the surface tension of the reaction liquidis not particularly limited, but it is preferable that the lower limitof the surface tension be greater than or equal to 1 mN/N at thetemperature of 25° C. It is possible to measure the surface tensionthrough the method described in Examples.

First Ink

The first ink contains a color material. The content of the colormaterial in the first ink with respect to a total 100 mass % of thefirst ink is preferably 2 mass % to 15 mass %, and more preferably 3mass % to 13 mass %. By setting the content of the color material to bewithin the above-described range, the obtained recorded matter tends tobe more excellent in the bleeding resistance and the color developingproperty.

Second Ink

The second ink contains a color material. The content of the colormaterial in the second ink with respect to a total 100 mass % of thesecond ink is preferably 2 mass % to 15 mass %, and more preferably 3mass % to 13 mass %. By setting the content of the color material to bewithin the above-described range, the obtained recorded matter tends tobe more excellent in the bleeding resistance and the color developingproperty.

Color Material

The color material that can be contained in the first ink and the secondink will be described hereinafter. The first ink and the second ink mayrespectively contain a single color material or two or more of colormaterials. In addition, it is preferable that the color material be adye or a pigment.

An example of a black color material used in a black ink includes carbonblack. The carbon black is not particularly limited, but examplesthereof include No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No.52, MA7, MA8, MA100, No. 2200B, or the like (all are manufactured byMitsubishi Chemical Corporation); Raven 5750, Raven 5250, Raven 5000,Raven 3500, Raven 1255, Raven 700, or the like (all are manufactured byCarbon Columbia); Regal 400R, Regal 330R, Regal 660R, Mogul L, Monarch700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100,Monarch 1300, Monarch 1400, or the like (manufactured by CABOT JAPANK.K.); Color Black FW1, Color Black FW2, Color Black FW2V, Color BlackFW18, Color Black FW200, Color Black S150, Color Black S160, Color BlackS170, Printex 35, Printex U, Printex V, Printex 140U, Special Black 6,Special Black 5, Special Black 4A, Special Black 4, or the like (all aremanufactured by Degussa).

Color materials used in a white ink are not particularly limited, butexamples thereof include C.I. Pigment Whites 6, 18, and 21. Otherexamples of pigments used in the white ink include alkaline earth metalsulfates such as barium sulfates; alkaline earth metal carbonates suchas calcium carbonates; silicas such as fine silicic acid or syntheticsilicate; metal compounds such as calcium silicate, alumina, hydratedalumina, titanium dioxide, and zinc oxide; talc; and clay.

Color materials used in an yellow ink are not particularly limited, butexamples thereof include C.I. Pigment Yellows 1, 2, 3, 4, 5, 6, 7, 10,11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83,93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128,129, 133, 138, 139, 147, 151, 153, 154, 167, 172, and 180.

Color materials used in a magenta ink are not particularly limited, butexamples thereof include C.I. Pigment Reds 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40,41, 42, (Ca), 48 (Mn), 57 (Ca), 57:1, 88, 112, 114, 122, 123, 144, 146,149, 150, 166, 168, 170, 171, 175, 176, 177, 178, 179, 184, 185, 187,202, 209, 219, 224, and 245, and C.I. Pigment Violets 19, 23, 32, 33,36, 38, 43, and 50.

Color materials used in a cyan ink are not particularly limited, butexamples thereof include C. I. Pigment Blues 1, 2, 3, 15, 15:1, 15:2,15:3, 15:34, 15:4, 16, 18, 22, 25, 60, 65, and 66, and C. I. Bat Blues 4and 60.

Other color materials except for magenta, cyan, and yellow colormaterials are not particularly limited, but examples thereof includeC.I. Pigment Greens 7 and 10, C.I. Pigment Browns 3, 5, 25, and 26, andC.I. Pigment Oranges 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43,and 63.

An example of a metallic color material used in a metallic ink includesa metallic pigment. Metal micro-particles can be used in the metallicink and examples of the metal include aluminum, aluminum alloy, andsilver. The metallic ink is an ink in which a pattern which is impartedto and formed on the recording medium has a metallic luster and themetallic pigment is a pigment that expresses the metallic luster.

It is preferable that at least any one of the first ink and the secondink be a color ink containing a color material or a black ink containinga black color material. In addition, it is more preferable that any oneof the first ink and the second ink be the color ink containing thecolor material or the black ink containing the black color material, andthe other one of the first ink and the second ink be a white inkcontaining a white color material. By setting the ink set in thismanner, it is possible to obtain the color developing property withrespect to a recording medium except for the white color when performingthe recording on the non-absorptive recording medium or thelow-absorptive recording medium. For example, a transparent medium, acolor medium, a metallic medium, and the like are suitably used.

It is preferable that the first ink be the white ink containing thewhite color material and the second ink be the color ink containing thecolor material or the black ink containing the black color material. Bysetting the ink set in this manner, it is possible to obtain the colordeveloping property with respect to a recording medium except for thewhite color when performing the recording on the non-absorptiverecording medium or the low-absorptive recording medium. For example,the transparent medium, the color medium, the metallic medium, and thelike are suitably used.

The ratio A of the number of moles (unit: mol) of the coagulantcontained in the reaction liquid to the total mass (unit: g) of thecolor material contained in the first ink and the second ink ispreferably 100:1 to 5000:1, and more preferably 500:1 to 4000:1. Bysetting the ratio A to be greater than or equal to 100:1, it is possibleto prevent precipitation of the reaction liquid, cloudiness due to thereaction liquid, stickiness, and the generation of a bad odor. Inaddition, by setting the ratio A to be less than or equal to 5000:1, itis possible to suppress the bleeding when superimposing inks.

The ratio B of the number of moles (unit: mol) of the polyvalent metalsalt contained in the reaction liquid to the total mass (unit: g) of thecolor material contained in the first ink and the second ink ispreferably 300:1 to 5000:1, and more preferably 500:1 to 5000:1. Bysetting the ratio B to be greater than or equal to 300:1, it is possibleto prevent precipitation of the polyvalent metal salt, cloudiness due tothe polyvalent metal salt, stickiness, and the generation of a bad odor.In addition, by setting the ratio B to be less than or equal to 5000:1,it is possible to suppress the bleeding when superimposing inks.

The ratio C of the number of moles (unit: mol) of the organic acidcontained in the reaction liquid to the total mass (unit: g) of thecolor material contained in the first ink and the second ink ispreferably 100:1 to 800:1, and more preferably 100:1 to 700:1. Bysetting the ratio C to be greater than or equal to 100:1, it is possibleto prevent precipitation of the organic acid, cloudiness due to theorganic acid, stickiness, and the generation of a bad odor. In addition,by setting the ratio C to be less than or equal to 800:1, it is possibleto suppress the bleeding when superimposing inks.

The ratio D of the mass (unit: g) of at least one selected from thegroup consisting of a component of a receiving layer and the a cationicresin which are contained in the reaction liquid, to the mass (unit: g)of the color material contained in the first ink is preferably 1:1 to10:1, and more preferably 1:1 to 5:1. By setting the ratio D to begreater than or equal to 1:1 (the former), the bleeding tends to befurther suppressed as the function of suppressing the bleeding of thecoagulant is further assisted. In addition, by setting the ratio D to beless than or equal to 10:1 (the former), the storage stability of thereaction liquid, or the clogging reliability when being coated with theink jet tends to be more excellent.

As these are apparent from table 2, the ratio A is the ratio of (thecolor material: the coagulant), the ratio B is the ratio of (the colormaterial: the polyvalent metal salt), the ratio C is the ratio of (thecolor material: the organic acid), the ratio D is the ratio of (thecolor material: at least one kind that is selected from group).Each ratio (A, B, C, D) are comparison at unit mass of the reactionliquid and the unit mass of the first ink and the unit mass of thesecond ink.

When using the pigment as the above-described color material, it ispreferable that the pigment be added to the ink as a pigment dispersingliquid which is obtained by dispersing the pigment in water using adispersant, or as a pigment dispersing liquid which is obtained bydispersing a self-dispersion type surface-treated pigment in which ahydrophilic group is introduced to the surface of the pigment particleusing a chemical reaction, or obtained by dispersing a pigment coveredwith a polymer.

The above-described dispersant is not particularly limited, but forexample, polymeric dispersants (proteins such as glue, gelatin, casein,and albumin; natural gums such as gum arabic and tragacanth; glucosidessuch as saponin; alginic acid ferments such as alginic acid, propyleneglycol ester, triethanolamine alginate, and ammonium alginate; cellulosederivatives such as methyl cellulose, carboxymethyl cellulose, and ethylhydroxy cellulose; polyvinyl alcohols; polypyrrolidones; acrylic-basedresins such as polyacrylic acid, acrylic acid-acrylonitrile copolymers,potassium acrylate-acrylonitrile copolymers, vinyl acetate-acrylic estercopolymers, and acrylic acid-acrylic acid ester copolymers;styrene-acrylic resins such as styrene-acrylic acid copolymers,styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylicacid ester copolymers, styrene-m-methyl-styrene-acrylic acid copolymers;vinyl acetate-based copolymers such as styrene-maleic acid copolymers,styrene-maleic anhydride copolymers, vinyl naphthalene-acrylic acidcopolymers, vinyl acetate-ethylene copolymers, vinyl acetate-fatty acidvinyl ethylene copolymers, vinyl acetate-maleic acid ester copolymers,vinyl acetate-crotonic copolymers, vinyl acetate-acrylic acidcopolymers, and salts thereof) or surfactants (various anionicsurfactants, nonionic surfactants, amphoteric surfactants) can be used.

The above-described self-dispersion type surface-treated pigment towhich the hydrophilic group is introduced is a pigment which can bedispersed or dissolved in the water without using the dispersant throughthe surface treatment in which a carboxyl group or a salt thereof isdirectly connected to the surface of the pigment. Specifically, it ispossible to obtain a grafted functional group or a grafted moleculecontaining the functional group by grafting the functional group or themolecule containing the functional group on the surface of the pigmentthrough physical treatment such as vacuum plasma or chemical treatmentusing an oxidizing agent such as sodium hypochlorite or ozone. Thefunctional group grafted on a pigment particle may be a single kind ormultiple kinds. The type and degree of the grafted functional group maybe appropriately set while considering dispersion stability in the ink,color density, and drying properties in a front face of an ink jet head.

In addition, the pigment covered with the above-described polymer is notparticularly limited, but for example, after dispersing the pigmentusing the dispersant having a polymerizable group, it is possible toobtain the covered pigment by performing emulsion polymerization in thewater using a monomer (copolymerizable monomer) which is copolymerizablewith the dispersant and a photoradical polymerization initiator. Amongthe polymers, a monomer which has at least one selected from a groupconsisting of acryloyl group, methacryloyl group, a vinyl group, and anallyl group as double bonds, or an oligomer which is polymerizedaccording to a well-known polymerization method using a photo-radicalpolymerization initiator can be suitably used. For the emulsionpolymerization, a general method can be used and the polymerization isprogressed using a free radical generated by thermal decomposition of awater-soluble photoradical polymerization initiator in the presence ofan emulsifier.

The pigment configuring the above-described pigment dispersing liquidand the dispersant may be respectively used alone or in a combination oftwo or more thereof.

Resin Emulsion

In a case where the ink used in the present embodiment contains apigment as a color material, it is preferable to further contain a resinemulsion. With the use of the resin emulsion, resins themselves and aresin and a pigment in the resin emulsion are mutually fused inaccordance with drying of the ink to fix the pigment to the recordingmedium. Therefore, it is possible to enhance friction resistance andadhesiveness of the image portion of the recorded matter. Among theresin emulsions, a urethane resin emulsion and acrylic resin emulsionare preferable, and the urethane resin emulsion is more preferable.Accordingly, the ink becomes excellent in fixing properties, therebybecoming excellent in the friction resistance and the adhesiveness ofthe recorded matter as well.

In a case where the resin emulsion contains the ink, the resin emulsionbecomes excellent in the friction resistance of the recorded medium bysufficiently fixing the ink on the recording medium through theformation of a resin coating film on the recording medium. For thisreason, it is preferable that the resin emulsion contain a thermoplasticresin. In particular, the urethane resin emulsion has high flexibilityin design, and thus, it is easy to obtain desired physical properties ofthe film.

In addition, an anionic resin emulsion is also preferable. A resincontaining the anionic resin emulsion is not particularly limited, butexamples thereof include a homopolymer or a copolymer of (meth)acrylicacid, (meth)acrylic acid ester, acrylonitrile, cyanoacrylate,acrylamide, olefin, styrene, vinyl acetate, vinyl chloride, vinylalcohol, vinyl ethers, vinyl pyrrolidone, vinyl pyridine, vinylcarbazole, vinyl imidazole, and vinylidene chloride; fluororesins; andnatural resins. Among these, at least one selected from a groupconsisting of a (meth)acrylic-based resin and a styrene-(meth)acrylicacid copolymer-based resin is preferable, at least one selected from agroup consisting of an acrylic-based resin and a styrene-acrylic acidcopolymer-based resin is more preferable, and the styrene-acrylic acidcopolymer-based resin is still more preferable. The above-describedcopolymer may be in any form of a random copolymer, a block copolymer,an alternating copolymer, and a graft copolymer.

A resin emulsion obtained using a well-known material and through awell-known production method may be used and a commonly available resinemulsion may be used as the resin emulsion. The commonly available resinemulsion is not particularly limited, but examples thereof includeMowinyl 966A (trade name of an acrylic resin emulsion, manufactured byNippon Synthetic Chemical Industry Co., Ltd.); Microgel E-1002 andMicrogel E-5002 (all are trade names, manufactured by Nippon Paint Co.,Ltd.); Boncoat 4001 and Boncoat 5454 (all are trade names, manufacturedby DIC Corporation); SAE 1014 (trade name, manufactured by ZeonCorporation); Saivinol SK-200 (trade name, manufactured by SaidenChemical Industry Co., Ltd.); Joncryl 7100, Joncryl 390, Joncryl 711,Joncryl 511, Joncryl 7001, Joncryl 632, Joncryl 741, Joncryl 450,Joncryl 840, Joncryl 62J, Joncryl 74J, Joncryl HRC-1645J, Joncryl 734,Joncryl 852, Joncryl 7600, Joncryl 775, Joncryl 537J, Joncryl 1535,Joncryl PDX-7630A, Joncryl 352J, Joncryl 352D, Joncryl PDX-7145, Joncryl538J, Joncryl 7640, Joncryl 7641, Joncryl 631, Joncryl 790, Joncryl 780,and Joncryl 7610 (all are trade names, manufactured by BASF Japan); andNK binder R-5HN (trade name of an acrylic resin emulsion, 44% of solidcontent, manufactured by Shin-Nakamura Chemical Co., LTD.). Among these,Mowinyl 966A which is the acrylic resin emulsion is preferable as itsufficiently satisfies the preferable physical property of the resinemulsion described above.

The resin emulsion may be used alone or in a combination of two or morethereof.

The content of the resin of the resin emulsion with respect to a total100 mass % of each ink is preferably 3 mass % to 15 mass %, morepreferably 7 mass % to 14 mass %, and still more preferably 8 mass % to13 mass %. By setting the content thereof to be within theabove-described range, the recorded matter tends to be more excellent inthe adhesiveness and the friction resistance and the ink tends to beexcellent in long-term storage stability, thereby the ink can beparticularly made to have low viscosity.

Solvent

It is preferable that the ink in the present embodiment further includea solvent. The solvent is not particularly limited, and for example, anorganic solvent or water can be used as the solvent.

Examples of water include water from which ionic impurities are removedas much as possible, for example, pure water or ultrapure water such asion-exchanged water, ultra-filtered water, reverse osmosis water, anddistilled water. In addition, use of water which is sterilized byirradiation with ultraviolet light, addition of hydrogen peroxide, orthe like can prevent generation of mold or bacteria during long-termpreservation of the ink. Accordingly, the storage stability tends to befurther improved.

A volatile water-soluble organic solvent is more preferable as theorganic solvent. The organic solvent is not particularly limited, butspecific examples thereof include alcohols or glycols such as glycerin,ethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol,pentanediol, 1,6-hexanediol, diethylene glycol mono-n-propyl ether,ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propylether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butylether, diethylene glycol mono-n-butyl ether, triethylene glycolmonobutyl ether, diethylene glycol mono-t-butyl ether, propylene glycolmonomethyl ether, propylene glycol monoethyl ether, propylene glycolmono-t-butyl ether, propylene glycol mono-n-propyl ether, propyleneglycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether,dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-n-propylether, dipropylene glycol mono-iso-propyl ether, diethylene glycoldimethyl ether, diethylene glycol diethyl ether, diethylene glycoldibutyl ether, diethylene glycol ethyl methyl ether, diethylene glycolbutyl methyl ether, triethylene glycol dimethyl ether, tetraethyleneglycol dimethyl ether, dipropylene glycol dimethyl ether, dipropyleneglycol diethyl ether, tripropylene glycol dimethyl ether, methanol,ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, 2-butanol,tert-butanol, iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, andtert-pentanol; N,N-dimethylformamide; N,N-dimethylacetamide;2-pyrrolidone; N-methyl-2-pyrrolidone; 2-oxazolidone;1,3-dimethyl-2-imidazolidinone; dimethyl sulfoxide; sulfolane; and1,1,3,3-tetramethyl urea.

The organic solvent may be used alone or in a combination of two or morethereof. The content of the organic solvent is not particularly limitedand can be appropriately set as necessary. Among these, it is preferableto use one or more selected from a group consisting of 1,2-hexanediol,triethylene glycol monobutyl ether, and dipropylene glycol mono-propylether.

Surfactant

It is preferable that the ink used in the present embodiment contain asurfactant. The surfactant is not particularly limited, but preferableexamples thereof include at least one selected from a group consistingof an acetylene glycol-based surfactant and a polysiloxane-basedsurfactant. By allowing the ink to contain these surfactants, it ispossible to realize high speed recording as the drying properties of theink adhered to the recording medium are enhanced.

Among these, the polysiloxane-based surfactant is more preferable sinceits solubility to the ink becomes high and foreign materials are hardlygenerated in the ink.

The above-described acetylene glycol-based surfactant is notparticularly limited, but preferable examples thereof include one ormore selected from 2,4,7,9-tetramethyl-5-decyne-4,7-diol and an alkyleneoxide adduct of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and2,4-dimethyl-5-decyne-4-ol and an alkylene oxide adduct of2,4-dimethyl-5-decyne-4-ol. These are commonly available products suchas an Olfine 104 series or an E series such as Olfine E1010 (trade name,manufactured by Air Products Japan, Inc.), and Olfine PD-002W, Surfynol465 or Surfynol 61 (trade name, manufactured by Nissin Chemical IndustryCo., Ltd.).

In addition, the polysiloxane-based surfactant is not particularlylimited, but examples thereof include BYK-347 and BYK-348 (BYK JapanKK).

Moisturizing Agent

It is preferable that the ink used in the present embodiment furthercontain a moisturizing agent (wetting agent). The moisturizing agent isnot particularly limited as long as the moisturizing agent is generallyused in the ink jet ink. The boiling point of the moisturizing agent ispreferably higher than or equal to 180° C., and more preferably higherthan or equal to 200° C. By setting the boiling point to be within theabove-described range, it is possible to impart favorable water-holdingproperties and wetting properties to the ink.

The moisturizing agent with the high boiling point is not particularlylimited, but examples thereof include ethylene glycol, propylene glycol,diethylene glycol, triethylene glycol, pentamethylene glycol,trimethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol,2-methyl-2,4-pentanediol, tripropylene glycol, polyethylene glycol withnumber average molecular weights of less than or equal to 2000,1,3-propylene glycol, isopropylene glycol, isobutylene glycol, glycerol,meso-erythritol, and pentaerythritol.

The moisturizing agent may be used alone or in a combination of two ormore thereof. By allowing the ink to contain the moisturizing agent withthe high boiling point, it is possible to obtain an ink that canmaintain fluidity and re-dispersibility for a long period of time evenif the pigment ink is left to stand in a state of coming into contactwith the air in an open state. Furthermore, such an ink hardly causesclogging of a nozzle in the middle of the recording or upon restartingafter interruption of the printing, using a recording apparatus, andtherefore, the ink becomes excellent in the discharge stability.

Other Components

In the ink used in the present embodiment, in order to favorablymaintain the storage stability and the discharge stability from thehead, to improve the clogging, and to prevent the ink fromdeterioration, it is possible to appropriately add various additivessuch as dissolution aids, viscosity modifiers, pH adjusting agents,antioxidants, preservatives, anti-mold agents, corrosion inhibitors, andchelating agents for capturing a metal ion that influences thedispersion. It is preferable that the ink used in the present embodimentbe a water-based ink which contains mostly water among the volatilecomponents in terms of safety.

Recording Medium

The ink set according to the present embodiment is used for recording onthe non-absorptive recording medium or the low-absorptive recordingmedium. An absorptive recording medium is inferior to water resistance,friction resistance, or the like, and in some cases, the manufacturingcost increases in a case of an absorptive recording medium which isconstituted by providing a receiving layer of an ink to the surface. Onthe other hand, the non-absorptive recording medium or thelow-absorptive recording medium is excellent in the water resistance,the friction resistance, and reducing the manufacturing cost compared tothe absorptive recording medium which is constituted by providing thereceiving layer of the ink on the surface. The bleeding is easilygenerated with the low-absorptive recording medium and the bleeding isfurther easily generated with the non-absorptive recording medium. It isdifficult to satisfy both the generation of the bleeding and theprinting speed, and therefore, it is effective to use the ink setaccording to the present embodiment and the non-absorptive recordingmedium is more efficient.

Here, the “low-absorptive recording medium” or the “non-absorptiverecording medium” refers to a recording medium having an amount of waterabsorption of less than or equal to 10 mL/m² from the start of contactuntil 30 msec in a Bristow's method. The Bristow's method is the mostcommon method as a method of measuring the amount of liquid absorptionin a short period of time and is also employed in JAPAN TAPPI. Thedetails of the test method are described in “JAPAN TAPPI Paper Pulp TestMethods, 2000 version”, Standard No. 51, “Paper and Paperboard—LiquidAbsorption Test Method—Bristow's method”.

In addition, the non-absorptive recording medium or the low-absorptiverecording medium can also be classified in accordance with wettabilityof water on a recording surface. For example, the recording medium canbe characterized by dripping 0.5 μL of a water droplet to the recordingsurface of the recording medium to measure the reduction rate of acontact angle (comparing a contact angle at 0.5 msec after impact to acontact angle at 5 sec after the impact). More specifically, ascharacteristics of the recording medium, the non-absorbency of the“non-absorptive recording medium” indicates that the above-describedreduction rate is less than 1% and the low-absorbency of the“low-absorptive recording medium” indicates that the reduction rate is1% to less than 5%. In addition, the absorbency indicates that theabove-described reduction rate is greater than or equal to 5%. It ispossible to measure the contact angle using Portable Contact Angle MeterPCA-1 (manufactured by Kyowa Interface Science Co., Ltd.) or the like.

The low-absorptive recording medium is not particularly limited, but anexample thereof includes coated paper in which a coating layer forreceiving an oil-based ink is provided on the surface. The coated paperis not particularly limited, but examples thereof include recordingpapers such as art paper, coated paper, and matte paper.

The non-absorptive recording medium is not particularly limited, butexamples thereof include a base material such as a plastic film or paperand which has no absorptive layer of an ink to which plastic is coated;or a base material to which a plastic film is attached. Examples of theplastic referred herein include polyvinyl chloride, polyethyleneterephthalate, polycarbonate, polystyrene, polyurethane, polyethylene,and polypropylene.

In addition to the above-described recording media, ink non-absorbent orlow-absorbent recording media such as glass or plates of metals such asiron, silver, copper, and aluminum can also be used.

Recording Method

The recording method according to the present embodiment includes areaction liquid imparting step of imparting a reaction liquid to anon-absorptive recording medium or a low-absorptive recording medium; afirst step of imparting a first ink to the top of the reaction liquid;and a second step of imparting a second ink to the top of the first inkusing the above-described ink set.

FIGURE is a side view schematically showing an example of a whole inkjet recording apparatus 1 that can be used in the present embodiment. Asshown in FIGURE, the ink jet recording apparatus 1 has a feeding unit10, a transporting unit 20, a recording unit 30, a drying device 90, anda discharging unit 70 of a recording medium. In addition, the ink jetrecording apparatus 1 also may have a pre-heater, which is not shown, toheat the recording medium F from the beginning.

Of these, the drying device 90 has a first drying unit 40 which performsa step of drying the recording medium and a second drying unit 50 whichdries a recorded matter obtained through the recording method accordingto the present embodiment.

In addition, the feeding unit 10 is provided such that the recordingmedium F can be fed to the transporting unit 20. Specifically, thefeeding unit 10 has roll medium holder 11 which holds recording media F.The feeding unit is configured such that the recording medium F can befed to the transporting unit 20 in a downstream side in a feedingdirection Y by rotating the recording medium F. The recording medium Fis not limited to have a roll shape.

Furthermore, the transporting unit 20 is provided such that therecording medium F which is fed from the feeding unit 10 can betransported to the recording unit 30. Specifically, the transportingunit 20 has a first feeding roller 21 and is configured such that thefed recording medium F can be further transported to the recording unit30 in the downstream side in the feeding direction Y.

In addition, the recording unit 30 is provided such that the reactionliquid can be imparted to the recording medium F which is fed from thetransporting unit 20 and the ink can be discharged for the recording.Specifically, the recording unit 30 has a head 31 that performs thereaction liquid imparting step; a head 32 that performs the first step;a recording head 33 that performs the second step; and a platen 34 as amedium supporting unit. The method of imparting the reaction liquid andthe ink is not limited to the ink jet, and in particular, the reactionliquid may be imparted through roller coating, press coating, or thelike. The ink jet is preferable in that it is possible to highlyprecisely impart an imparting position or an imparting amount to arequired area.

Of these, the platen 34 is provided such that the recording medium F canbe supported from a back surface. In addition, the platen 34 is providedwith a first drying unit 40 that dries the reaction liquid imparted tothe recording medium F and the ink discharged to the recording medium F.Furthermore, a second feeding roller 43 is provided in the downstreamside in the feeding direction Y from the platen 34. The second feedingroller 43 is configured such that the recorded recording medium F can befed to the second drying unit 50 in the downstream side in the feedingdirection Y.

In addition, the second drying unit 50 is configured such that it ispossible to further dry the reaction liquid imparted to the recordingmedium F and the ink discharged to the recording medium F. Furthermore,a third feeding roller 65 is provided in the vicinity of an outlet 64 ofthe second drying unit 50. The third feeding roller 65 is disposed so asto come into contact with the back surface of the recording medium F andis configured such that it is possible to feed the recording medium F tothe discharging unit 70 in the downstream side in the feeding directionY.

Furthermore, the discharging unit 70 is provided such that it ispossible to further feed the recording medium F which is fed from thesecond drying unit 50 in the downstream side of the feeding direction Yand to discharge the fed recording medium F to the outside of the inkjet recording apparatus 1. Specifically, the discharging unit 70 has afourth feeding roller 71, a fifth feeding roller 72, a sixth feedingroller 73, a seventh feeding roller 74, and a winding roller 75. Ofthese, the fourth feeding roller 71 and the fifth feeding roller 72 aredisposed so as to coming into contact with the surface of the recordingmedium F. In addition, the sixth feeding roller 73 and the seventhfeeding roller 74 are disposed so as to be paired with each other. Therecording medium F which is discharged by the sixth feeding roller 73and the seventh feeding roller 74 is provided to be wound by the windingroller 75.

Reaction Liquid Imparting Step

The reaction liquid imparting step is a step of imparting a reactionliquid on a non-absorptive recording medium or a low-absorptiverecording medium. The imparting means is not particularly limited, butroller coating, spray coating, and ink jet coating can be used. Duringthe reaction liquid imparting step or after the reaction liquidimparting step, there may be a step of drying at least a portion of thereaction liquid coated on the recording medium.

The amount of the reaction liquid imparted to the recording medium ispreferably 1 mg/inch² to 10 mg/inch², and more preferably 1 mg/inch² to5 mg/inch². By setting the imparted amount of the reaction liquid to bewithin the above-described range, the obtained recorded matter tends tobe excellent in the bleeding resistance.

The amount of the coagulant imparted to the recording medium ispreferably 0.5×10⁻⁴ to 15×10⁻⁴ mmol/inch² (50 to 1,500 nmol/inch²), andmore preferably 0.65×10⁻⁴ mmol/inch² or more, and further preferably1×10⁻⁴ mmol/inch² or more, and further preferably 1.5×10⁻⁴ mmol/inch² ormore, and further preferably 2×10⁻⁴ mmol/inch² or more, and furtherpreferably 3×10⁻⁴ mmol/inch² or more. And the amount of the coagulantimparted to the recording medium is more preferably 10.8×10⁻⁴ mmol/inch²or less, and further preferably 10×10⁻⁴ mmol/inch² or less, and furtherpreferably 5×10⁻⁴ mmol/inch² or less, By setting the imparted amount ofthe coagulant to be within the above-described range, the obtainedrecorded matter tends to be excellent in the image quality et al and thevalue of later ratio F, G, H tend to be set in later ranges. The amountof the reaction liquid or the coagulant imparted to the recording mediumare an amount of the reaction liquid or the coagulant imparted to therecording medium where the first ink and the second ink are impartedcoming into contact.

First Step

The first step is a step of imparting a first ink to the top of thereaction liquid. At this time, the first ink can be promptly coagulatedas the reaction liquid and the first ink are directly reacted to eachother and the reaction liquid does not have to be completely dried.Since the reaction liquid does not have to be completely dried or doesnot have to be dried at all, it is possible to start the imparting ofthe first ink early, thereby achieving the high recording speed. Duringthe first step or after the first step, there may be a step of drying atleast a portion of the reaction liquid and the first ink which arecoated on the recording medium.

The amount of the imparted first ink in the first step is preferably 2mg/inch² to 20 mg/inch², and more preferably 5 mg/inch² to 15 mg/inch².By setting the imparted amount of the first ink to be within theabove-described range, the obtained recorded matter tends to beexcellent in the bleeding resistance, clogging reliability, andstickiness.

Second Step

The second step is a step of imparting a second ink to the top of thefirst ink. At this time, the reaction liquid and the first ink do nothave to be completely dried. By imparting the second ink in a statewhere the first ink is not completely dried, it is possible to react thesecond ink with the reaction liquid even on the top of the first ink,and it is possible to achieve the high recording speed as the second inkcan be imparted while suppressing the bleeding even if the reactionliquid and the first ink are not completely dried. Before the secondstep, there may be a step of drying at least a portion of the reactionliquid and the first ink which are coated on the recording medium, andit is preferable to have a step of drying a portion thereof instead ofcompletely drying thereof. In addition, during the second step or afterthe second step, there may be a step of drying the second ink which iscoated on the recording medium.

The amount of the imparted second ink in the second step is preferably 2mg/inch² to 20 mg/inch², and more preferably 5 mg/inch² to 15 mg/inch².By setting the imparted amount of the second ink to be within theabove-described range, the obtained recorded matter tends to beexcellent in the bleeding resistance, clogging reliability, andstickiness.

In the first step and the second step, the total amount of the colormaterials contained in the first ink and the second ink imparted to therecording medium is preferable 0.5 to 3 mg/inch², and more preferably 1mg/inch² or more, and further preferably 1.5 mg/inch² or more, andfurther preferably 2.5 mg/inch² or less.

In the first step, the amount of the color material contained in thefirst ink imparted to the recording medium is preferable 0.1 to 2.5mg/inch², and more preferably 0.2 mg/inch² or more, and furtherpreferably 0.5 mg/inch² or more, and further preferably 1 mg/inch² ormore, and further preferably 2 mg/inch² or less. These amounts are atarea in the recording medium which the first ink and the second ink isimparted into contact with. By setting these imparted amounts to bewithin the above-described range, the obtained recorded matter tends tobe excellent in the image quality and the value of later ratio E, F, G,H tends to be set in later ranges.

The amount of the color material is preferably at area in the recordingmedium which the first ink and the second ink is imparted into contactwith, and the amount of the color material is most large.

The total amount of the color materials is preferably at area in therecording medium which the first ink and the second ink is imparted intocontact with, and the amounts of the color materials are most large.

In these, the obtained recorded matter tends to be excellent in theimage quality.

In the first step and the second step, it is possible to discharge thefirst ink or the second ink from nozzles of a line head or a serial headthrough an ink jet method to make the first ink or the second ink toadhere to the recording medium. In a line system using the line head, itis possible to record the image on the recording medium by fixing thehead to move the recording medium along a sub scanning direction (alongitudinal direction or a transporting direction of the recordingmedium) and by discharging ink droplets from the nozzle opening of thehead cooperatively with the movement. In addition, in a serial systemusing the serial head, it is possible to record the image on therecording medium by moving the head along a main scanning direction (ahorizontal direction or a width direction of the recording medium) andby discharging ink droplets from the nozzle opening of the headcooperatively with the movement.

In the second step, the volatilization amount of a volatile componentcontained in the reaction liquid and the first ink which are imparted tothe non-absorptive recording medium or the low-absorptive recordingmedium at the time of imparting the second ink with respect to a 100total mass % of a volatile component contained in the reaction liquidand the first ink before the imparting is preferably less than or equalto 95 mass %, more preferably less than or equal to 85 mass %, and stillmore preferably less than or equal to 80 mass %. In addition, thevolatilization amount thereof is still more preferably less than orequal to 60 mass %, still more preferably less than or equal to 50 mass%, and still more preferably less than or equal to 30 mass % in terms ofobtaining more excellent recording speed while obtaining excellentclogging reliability. Meanwhile, the volatilization amount thereof ispreferably greater than or equal to 5 mass %, more preferably greaterthan or equal to 10 mass %, particularly preferably 50 mass %, and stillmore preferably greater than or equal to 60 mass % in terms of achievingmore excellent suppression of the bleeding. Here, the “reaction liquidbefore the imparting” refers to a reaction liquid before imparting thereaction liquid which is to be coated on the recording medium in thereaction liquid imparting step and the “ . . . first ink before theimparting” refers to a first ink before imparting the first ink which isto be coated on the recording medium in the first step. By setting thevolatilization amount of the volatile component to be less than or equalto 95 mass %, it is possible to effectively react the reaction liquidwith the second ink, thereby achieving the high recording speed. Thevolatilization amount of the volatile component can be obtained throughthe method described in Examples.

The ratio E of the number of moles (unit: mol) of a coagulant containedin the reaction liquid per unit area in an area where the first ink andthe second ink are imparted on the non-absorptive recording medium orthe low-absorptive recording medium in a superimposed manner, to thetotal mass (unit: g) of a color material contained in the first ink andthe second ink is preferably 800:1 to 31000:1, more preferably 800:1 to16000:1, and still more preferably 1600:1 to 5100:1. By setting theratio E to be greater than or equal to 800:1, it is possible to preventprecipitation of the reaction liquid, cloudiness due to the reactionliquid, stickiness, and the generation of a bad odor. By setting therate E to be less than or equal to 31000:1, it is possible to suppressthe bleeding when superimposing inks. The ratio E can be controlled bythe imparting amount of the first ink, the second ink, and the reactionliquid.

The ratio F of the number of moles (unit: mol) of the polyvalent metalsalt contained in the reaction liquid per unit area in theabove-described area on the non-absorptive recording medium or thelow-absorptive recording medium, to the total mass (unit: g) of thecolor material contained in the first ink and the second ink ispreferably 1000:1 to 31000:1, more preferably 1000:1 to 15000:1, andstill more preferably 1000:1 to 5100:1. By setting the ratio F to begreater than or equal to 1000:1, it is possible to prevent precipitationof the polyvalent metal salt, cloudiness due to the polyvalent metalsalt, stickiness, and the generation of a bad odor. By setting the ratioF to be less than or equal to 31000:1, it is possible to suppress thebleeding when superimposing inks. The ratio F can be controlled by theimparting amount of the first ink, the second ink, and the reactionliquid.

The ratio G of the number of moles (unit: mol) of the organic acidcontained in the reaction liquid per unit area in the above-describedarea on the non-absorptive recording medium or the low-absorptiverecording medium, to the total mass (unit: g) of the color materialcontained in the first ink and the second ink is preferably 800:1 to5500:1, more preferably 800:1 to 1700:1, and still more preferably1000:1 to 1700:1. By setting the ratio G to be greater than or equal to800:1, it is possible to prevent precipitation of the organic acid,cloudiness due to the organic acid, stickiness, and the generation of abad odor. By setting the ratio G to be less than or equal to 5500:1, itis possible to suppress the bleeding when superimposing inks. The ratioG can be controlled by the imparting amount of the first ink, the secondink, and the reaction liquid.

The ratio H of the mass (unit: g) of at least one selected from thegroup consisting of the component of the receiving layer, and thecationic resin, which are contained in the reaction liquid per unit areaof the above-described area on the non-absorptive recording medium orthe low-absorptive recording medium, to the mass (unit: g) colormaterial contained in the first ink is preferably 7:1 to 70:1, and morepreferably 7:1 to 50:1. By setting the ratio H to be greater than orequal to 7:1 (the former), the suppression of the bleeding tends to bemore excellent. By setting the ratio H to be less than or equal to 70:1(the former), there is a tendency that it is excellent in efficientlyimparting the reaction liquid. The ratio H can be controlled by theimparting amount of the first ink and the reaction liquid. As these areapparent from table 3 to 5, the ratio E is the ratio of (the colormaterial: the coagulant), the ratio F is the ratio of (the colormaterial: the polyvalent metal salt), the ratio G is the ratio of (thecolor material: the organic acid), the ratio H is the ratio of (thecolor material: at least one kind that is selected from group).

In the recording method according to the present embodiment, it ispreferable that the temperature of the surface of the recording mediumin the first step and the second step be 10° C. to 65° C. In addition,the temperature thereof is more preferably lower than or equal to 50°C., and still more preferably lower than or equal to 40° C. in terms ofobtaining more excellent clogging reliability. Meanwhile, thetemperature thereof is more preferably higher than or equal to 20° C.,still more preferably higher than or equal to 40° C., and particularlypreferably higher than or equal to 50° C. in terms of achieving moreexcellent recording speed. By setting the temperature of the surface ofthe recording medium to be within the above-described range, theclogging reliability and the recording speed tend to be particularlyexcellent.

EXAMPLES

Hereinafter, the invention will be described in detail using Examplesand Comparative Examples. The present invention is not limited to thefollowing Examples.

Materials for Reaction Liquid and Ink

Main materials for the reaction liquid and the ink used in the followingExamples and Comparative Examples are as follows.

Pigment

Titanium dioxide: metal oxide, NanoTek® slurry

manufactured by C.I. Kasei Co., Ltd.

Cyan pigment: C. I. Pigment Blue 15:3

Polyvalent Metal Salt

Magnesium sulfate heptahydrate (molecular weight 246.47 g/mol)

Calcium acetate monohydrate (molecular weight 176.18 g/mol)

Calcium nitrate tetrahydrate (molecular weight 164.09 g/mol)

Organic Acid

Succinic acid (molecular weight 118.09 g/mol)

Surfactant

BYK 348 (silicone surfactant, manufactured by BYK Japan KK)

Resin Emulsion

Joncryl 62J (acrylic styrene-based resin, manufactured by BASF JapanLtd.)

Component of Receiving Layer

Anionic colloidal silica (manufactured by Nissan Chemical Industries,Ltd., “SNOWTEX ZL”)

Cationic Resin

Cationic resin emulsion (manufactured by UNITIKA LTD., “ArobaseCD-1200”)

Organic Solvent

1,2-hexane diol

Moisturizing Agent

Propylene glycol

Preparation of Reaction Liquid and Ink

Each of the materials was mixed in compositions (mass %) shown in thefollowing Table 1 and the mixture was sufficiently stirred to obtain areaction liquid, a first ink, and a second ink.

TABLE 1 Reaction liquid Ink 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 12 Polyvalent Magnesium 0.8 1.6 4.8 16 0 0 0 0 0 0 0 1.6 1.6 1.6 1.6 0 00 0 metal salt sulfate heptahydrate Calcium 0 0 0 0 1.1 3.4 0 0 0 0 0 00 0 0 0 0 0 0 acetate monohydrate Calcium 0 0 0 0 0 0 1.5 4.6 0 0 0 0 00 0 0 0 0 0 nitrate tetrahydrate Organic Succinic 0 0 0 0 0 0 0 0 2.36.9 13.8 0 0 0 0 0 0 0 0 acid acid Pigment White 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 10 0 pigment (titanium dioxide) Color 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 4 pigment (cyan) Surfactant BYK 348 0.6 0.6 0.6 0.6 0.6 0.60.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.1 0.6 0.6 0.6 0.6 Resin Joncryl 62J 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 2 emulsion Component Anionic 0 0 0 0 00 0 0 0 0 0 5 0.1 0 0 0 5 0 0 which colloidal becomes silica receivinglayer Cationic Cationic 0 0 0 0 0 0 0 0 0 0 0 0 5 0 0 0 5 0 0 resinresin emulsion Organic 1,2-hexane 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 3solvent diol Moisturizing Propylene 20 20 20 20 20 20 20 20 20 20 20 2020 20 20 20 20 10 15 Agent glycol Water Balance Balance Balance BalanceBalance Balance Balance Balance Balance Balance Balance Balance BalanceBalance Balance Balance Balance Balance Balance Surface tension of 35 3535 35 35 35 35 35 35 35 35 35 35 35 55 35 35 — — reaction liquid (mN/m)Method of Measuring Surface Tension

The surface tension of the reaction liquid was measured using a surfacetensiometer (manufactured by Kyowa Interface Science Co., Ltd., surfacetensiometer CBVP-Z or the like) through a Wilhelmy method at a solutiontemperature of 25° C.

Preparation of Ink Sets

Ink sets were obtained by combining the obtained reaction liquid, firstink, and second ink as in Table 2.

TABLE 2 Comparative Examples Examples 1 2 3 4 5 6 7 8 9 10 11 12 13 1415 16 17 18 19 1 2 3 4 Reaction 1 2 3 4 5 6 7 8 9 10 11 12 13 14 14 1414 9 15 16 16 17 16 liquid No. Ink No. of 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 2 1 1 1 1 1 1 First ink Ink No. of 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 1 22 2 2 2 2 Second ink Ratio A 4313 2157 719 216 3137 1015 1532 499 719240 120 2157 2157 2157 2157 2157 2157 719 2157 — — — — Ratio B 4313 2157719 216 3137 1015 1532 499 — — — 2157 2157 2157 2157 2157 2157 719 2157— — — — Ratio C — — — — — — — — 719 240 120 — — — — — — — — — — — —Ratio D — — — — — — — — — — — 2.00 1.96 — — — — — — — — — —

Examples 1 to 18, Comparative Examples 1 to 5

Converted equipment of PX-G930 (Seiko Epson Corp.) was used. Theconverted point is to install a heater to a platen so as to be able toheat a recording medium. A nozzle pitch is 180 dpi. The reaction liquid,the first ink, and the second ink of the ink set prepared in the abovewere discharged in this order from each head through the ink jet methodunder the recording conditions shown in Tables 1 to 3; and solidpatterns were adhered to a PET film “Lumirror S10” (trade name,thickness of 100 μm) manufactured by TORAY INDUSTRIES, INC. as thenon-absorptive recording medium or NP coating paper (manufactured byLintec Corporation) as the low-absorptive recording medium. At thistime, a pattern 1 to which only the reaction liquid was imparted, apattern 2 to which only the reaction liquid and the first ink wereimparted in a superimposed manner, and a pattern 3 to which the reactionliquid, the first ink, and the second ink were imparted in asuperimposed manner were formed. The pattern 2 and the pattern 3 aresimultaneously formed so as to come into contact with each other.

Specifically, in a case of forming the pattern 3, a reaction liquid wasimparted while adjusting the temperature of the recording medium to bethe temperatures in Tables 3 to 5 in advance to form a pattern(sub-pattern) constituting the reaction liquid; a first ink wassubsequently imparted on the sub-pattern constituting the reactionliquid to form a sub-pattern consisting the first ink; and then, asub-pattern constituting the second ink was formed on the sub-patternconstituting the first ink to form the pattern 3. The temperature of therecording medium was adjusted using the platen heater so as to maintainthe temperature to be the temperatures in Tables 3 to 5 even whileimparting the reaction liquid, the first ink, and the second ink. Inaddition, after the first step and before the start of the second step,the contents of the volatile components of the reaction liquid and thefirst ink on the recording medium were adjusted to be the values inTables 3 to 5 to perform the second step. Recording resolution was setto 720×720 dpi and the amount of the reaction liquid and the amount ofthe ink per dot were adjusted to be the imparting amount in the tables.

Volatilization Amount of Volatile Component of Reaction Liquid and FirstInk Before Second Step

The volatilization amount of the volatile component of the reactionliquid and the first ink in the pattern 3 after the first step andbefore the second step (when the recording medium was transported to theposition facing the head for the second ink) was calculated using thefollowing formula. Here, Af is a total imparting amount (mg) of thereaction liquid and the first ink of the area to which the reactionliquid and the first ink are imparted to the recording medium in asuperimposed manner. In addition, Ae is a total amount of residue of thereaction liquid and the first ink on the recording medium in a statewhere the reaction liquid and the first ink were dried (volatilized)until the recorded matter becomes a state to be ready for use.Furthermore, A is a total mass of the reaction liquid and the first inkon the recording medium immediately before the second step.Volatilization amount % of the volatile component=((Af−A)/(Af−Ae))×100

Af can be obtained from discharge data of the printer and the mass perdot as the imparting amount of the reaction liquid and the first ink inthe pattern 3. A can be obtained by measuring the mass of the recordingmedium when starting the imparting of the second ink and the mass of therecording medium before the step of the reaction liquid imparting stepto take the difference therebetween. When measuring the volatilizationamount of the volatile component, it is simple to use the recordingmedium which was prepared for the measurement. The measurement wasperformed using an electronic balance. When performing the measurement,the relationship between predetermined drying time and volatilizationamount at the time of heating and drying the reaction liquid and thefirst ink using the platen after the reaction liquid and the first inkwere imparted. When performing the recording using the recordingapparatus, it is possible to set a predetermined volatilization amountby setting the time between the imparting of the reaction liquid and thefirst ink and the imparting of the second ink to be any time of therelationship between the drying time and the volatilization amountobtained as above.

Evaluation

Bleeding when Recording First Ink and Second Ink in Superimposed Manner

Recorded matters which were recorded by varying the imparting amount ofthe second ink in the pattern 3 between 30% and 200% were obtained bysetting the value shown in Tables 3 to 5 as 100%. The portion where thepattern 3 and the pattern 2 of the obtained recorded matter come intocontact with each other was visually observed to evaluate bleeding whenrecording the first ink and the second ink in a superimposed mannerusing the following evaluation criteria. “200%” is a value obtained byassuming a maximum imparting amount of the total of a plurality ofcolors of inks in a case where a secondary color or more are recordedusing a plurality of color inks. It can be said that a recorded matterin which the bleeding is suppressed is obtained when using the pluralityof color inks if the score in the following evaluation criteria is A orAA.

Evaluation Criteria

AA: There is no color mixing even if the imparting amount of the secondink is 200%.

A: There is no color mixing if the imparting amount of the second ink isup to 100%.

B: There is no color mixing if the imparting amount of the second ink isup to 50%.

C: There is color mixing occurring even if the imparting amount of thesecond ink is 30%.

Precipitation of Reaction Liquid on Recording Medium

The pattern 1 was visually observed to evaluate the precipitation of thereaction liquid on the recording method using the following evaluationcriteria.

Evaluation Criteria

A: The precipitation is not recognized.

B: The precipitation is recognized, but the cloudiness is notrecognized.

C: The precipitation and the cloudiness are recognized.

Cloudiness of Image Portion

The pattern 3 was visually observed by evaluating the cloudiness of theportion (image portion) to which an ink was imparted using the followingevaluation criteria.

Evaluation Criteria

A: The cloudiness is not recognized.

B: The cloudiness is recognized.

Unevenness of First Ink on Recording Medium

The pattern 2 was visually observed to evaluate the unevenness of thefirst ink on the recording medium using the following EvaluationCriteria.

Evaluation Criteria

A: Cohesion unevenness is not recognized in the first ink.

B: Slight cohesion unevenness is recognized in the first ink.

C: Considerable cohesion unevenness is recognized in the first ink.

Bad Odor of Recorded Matter

Sensory evaluation was performed on the pattern 3 to evaluate the badodor of the recorded matter using the following evaluation criteria.

Evaluation Criteria

A: There is no bad odor.

B: There is a slight bad odor.

C: There is a considerable bad odor.

Stickiness of Recorded Matter

The patterns 3 between recorded surfaces were superimposed to evaluatethe stickiness of the recorded matter using the following evaluationcriteria.

Evaluation Criteria

A: There is no adherence between two printed surfaces even if they areleft to stand for 1 day in a state of being superimposed (there is nostickiness).

B: After the two printed surfaces are left to stand for 1 day in thestate of being superimposed, the two printed surfaces are adhered toeach other if one surface is lifted, but they are peeled off within 1minute (there is slight stickiness).

C: After the two printed surfaces are left to stand for 1 day in thestate of being superimposed, the two printed surfaces are adhered toeach other if one surface is lifted, and they are not peeled off evenafter 1 minute (there is stickiness).

Recording Speed

The recording speed was evaluated based on the recording speed at whichthe pattern 3 can be obtained, using the following evaluation criteria.

Evaluation Criteria

A: The pattern 3 can be recorded on an A4-size recording medium in lessthan 30 seconds.

B: The pattern 3 can be recorded on an A4-size recording medium in 30seconds to 1 minute.

C: The pattern 3 can be recorded on an A4-size recording medium if thetime exceeds 3 minutes.

Clogging Reliability

A nozzle after the pattern 3 was recorded on 50 sheets of A4-sizedrecording media were visually observed to evaluate the cloggingreliability using the following evaluation criteria.

Evaluation Criteria

A: Neither nozzle slip-out nor bent nozzle occurs even if the pattern 3is recorded on 50 sheets of the recording media.

B: The nozzle slip-out is not occurred, but the bent nozzle occurs ifthe pattern 3 is recorded on 50 sheets of the recording media.

C: The nozzle slip-out and the bent nozzle occur if to pattern 3 isrecorded on 50 sheets of the recording media.

TABLE 3 Example 1 Example 2 Example 3 Example 4 First Second FirstSecond First Second First Second Reaction ink ink Reaction ink inkReaction ink ink Reaction ink ink Ink liquid (white) (color) liquid(white) (color) liquid (white) (color) liquid (white) (color) Magnesium0.8 0 0 1.6 0 0 4.8 0 0 16 0 0 sulfate heptahydrate Calcium 0 0 0 0 0 00 0 0 0 0 0 acetate monohydrate Calcium 0 0 0 0 0 0 0 0 0 0 0 0 nitratetetrahydrate Succinic acid 0 0 0 0 0 0 0 0 0 0 0 0 White pigment 0 10 00 10 0 0 10 0 0 10 0 (titanium oxide) Color pigment 0 0 4 0 0 4 0 0 4 00 4 (cyan) Surfactant 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6Joncryl 62J 0 4 2 0 4 2 0 4 2 0 4 2 Anionic 0 0 0 0 0 0 0 0 0 0 0 0colloidal silica Cationic resin 0 0 0 0 0 0 0 0 0 0 0 0 emulsion1,2-hexane diol 0 3 3 0 3 3 0 3 3 0 3 3 Propylene 20 10 15 20 10 15 2010 15 20 10 15 glycol Water Balance Balance Balance Balance BalanceBalance Balance Balance Balance Balance Balance Balance RecordingLumirror S10 Lumirror S10 Lumirror S10 Lumirror S10 medium Surface Roomtemperature (25° C.) Room temperature (25° C.) Room temperature (25° C.)Room temperature (25° C.) temperature of recording me- dium duringrecording (heat assist) Volatilization 10% 10% 10% 10% amount ofvolatile component in second step Imparting amount 2 14 14 2 14 14 2 1414 2 14 14 (mg/inch²) Imparting amount 0 1.4 0.56 0 1.4 0.56 0 1.4 0.560 1.4 0.56 of color material (mg/inch²) Imparting amount 0.65 0 0 1.3 00 3.9 0 0 13 0 0 of coagulant (× 10⁻⁴ mmol/ inch²) Total imparting 0 0 00 0 0 0 0 0 0 0 0 amount of component which becomes receiving layer andcationic resin (mg/inch²) Ratio F 30154:1 15077:1 5026:1 1508:1 Ratio G— — — — Ratio H — — — — Unevenness of B A A A first ink on re- cordingmedium Bleeding when B A AA AA recording first ink and second ink insuper- imposed manner Precipitation of A A A B reaction liquid onrecording medium Cloudiness of A A A B recorded matter Bad odor of A A AA recorded matter Stickiness of A A A A recorded matter Recording speedA A A A Clogging A A A A reliability Example 5 Example 6 Example 7Example 8 First Second First Second First Second First Second Reactionink ink Reaction ink ink Reaction ink ink Reaction ink ink Ink liquid(white) (color) liquid (white) (color) liquid (white) (color) liquid(white) (color) Magnesium 0 0 0 0 0 0 0 0 0 0 0 0 sulfate heptahydrateCalcium 1.1 0 0 3.4 0 0 0 0 0 0 0 0 acetate monohydrate Calcium 0 0 0 00 0 1.5 0 0 4.6 0 0 nitrate tetrahydrate Succinic acid 0 0 0 0 0 0 0 0 00 0 0 White pigment 0 10 0 0 10 0 0 10 0 0 10 0 (titanium oxide) Colorpigment 0 0 4 0 0 4 0 0 4 0 0 4 (cyan) Surfactant 0.6 0.6 0.6 0.6 0.60.6 0.6 0.6 0.6 0.6 0.6 0.6 Joncryl 62J 0 4 2 0 4 2 0 4 2 0 4 2 Anionic0 0 0 0 0 0 0 0 0 0 0 0 colloidal silica Cationic resin 0 0 0 0 0 0 0 00 0 0 0 emulsion 1,2-hexane diol 0 3 3 0 3 3 0 3 3 0 3 3 Propylene 20 1015 20 10 15 20 10 15 20 10 15 glycol Water Balance Balance BalanceBalance Balance Balance Balance Balance Balance Balance Balance BalanceRecording Lumirror S10 Lumirror S10 Lumirror S10 Lumirror S10 mediumSurface Room temperature (25° C.) Room temperature (25° C.) Roomtemperature (25° C.) Room temperature (25° C.) temperature of recordingme- dium during recording (heat assist) Volatilization 10% 10% 10% 10%amount of volatile component in second step Imparting amount 2 14 14 214 14 2 14 14 2 14 14 (mg/inch²) Imparting amount 0 1.4 0.56 0 1.4 0.560 1.4 0.56 0 1.4 0.56 of color material (mg/inch²) Imparting amount 1.30 0 3.9 0 0 1.3 0 0 3.9 0 0 of coagulant (× 10⁻⁴ mmol/ inch²) Totalimparting 0 0 0 0 0 0 0 0 0 0 0 0 amount of component which becomesreceiving layer and cationic resin (mg/inch²) Ratio F 15077:1 5026:115077:1 5026:1 Ratio G — — — — Ratio H — — — — Unevenness of A A A Afirst ink on re- cording medium Bleeding when A AA A AA recording firstink and second ink in super- imposed manner Precipitation of A A A Areaction liquid on recording medium Cloudiness of A A A A recordedmatter Bad odor of A B A A recorded matter Stickiness of A A A Brecorded matter Recording speed A A A A Clogging A A A A reliability

TABLE 4 Example 9 Example 10 Example 11 Example 12 First Second FirstSecond First Second First Second Reaction ink ink Reaction ink inkReaction ink ink Reaction ink ink Ink liquid (white) (color) liquid(white) (color) liquid (white) (color) liquid (white) (color) Magnesium0 0 0 0 0 0 0 0 0 1.6 0 0 sulfate heptahydrate Calcium 0 0 0 0 0 0 0 0 00 0 0 acetate monohydrate Calcium 0 0 0 0 0 0 0 0 0 0 0 0 nitratetetrahydrate Succinic acid 2.3 0 0 6.9 0 0 13.8 0 0 0 0 0 White pigment0 10 0 0 10 0 0 10 0 0 10 0 (titanium oxide) Color pigment 0 0 4 0 0 4 00 4 0 0 4 (cyan) Surfactant 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.60.6 Styrene acrilic 0 4 2 0 4 2 0 4 2 0 4 2 resin Component 0 0 0 0 0 00 0 0 5 0 0 which becomes receiving layer Cationic resin 0 0 0 0 0 0 0 00 0 0 0 1,2-hexane diol 0 3 3 0 3 3 0 3 3 0 3 3 Propylene 20 10 15 20 1015 20 10 15 20 10 15 glycol Water Balance Balance Balance BalanceBalance Balance Balance Balance Balance Balance Balance BalanceRecording Lumirror S10 Lumirror S10 Lumirror S10 Lumirror S10 mediumSurface Room temperature (25° C.) Room temperature (25° C.) Roomtemperature (25° C.) Room temperature (25° C.) temperature of recordingme- dium during recording (heat assist) Volatilization 10% 10% 10% 10%amount of volatile component in second step Imparting amount 2 14 14 214 14 2 14 14 2 14 14 (mg/inch²) Imparting amount 0 1.4 0.56 0 1.4 0.560 1.4 0.56 0 1.4 0.56 of color material (mg/inch²) Imparting amount 3.90 0 10.8 0 0 21.6 0 0 1.3 0 0 of coagulant (× 10⁻⁴ mmol/ inch²) Totalimparting 0 0 0 0 0 0 0 0 0 0.1 0 0 amount of component which becomesreceiving layer and cationic resin (mg/inch²) Ratio F — — — 15077:1Ratio G 5026:1 1675:1 837:1 — Ratio H — — —   14:1 Unevenness of A A A Afirst ink on re- cording medium Bleeding when B A AA AA recording firstink and second ink in super- imposed manner Precipitation of A A A Areaction liquid on recording medium Cloudiness of A A A A recordedmatter Bad odor of A A A A recorded matter Stickiness of A A A Arecorded matter Recording speed A A A A Clogging A A A A reliabilityExample 13 Example 14 Example 15 Example 16 First Second First SecondFirst Second First Second Reaction ink ink Reaction ink ink Reaction inkink Reaction ink ink Ink liquid (white) (color) liquid (white) (color)liquid (white) (color) liquid (white) (color) Magnesium 1.6 0 0 1.6 0 01.6 0 0 1.6 0 0 sulfate heptahydrate Calcium 0 0 0 0 0 0 0 0 0 0 0 0acetate monohydrate Calcium 0 0 0 0 0 0 0 0 0 0 0 0 nitrate tetrahydrateSuccinic acid 0 0 0 0 0 0 0 0 0 0 0 0 White pigment 0 10 0 0 10 0 0 10 00 10 0 (titanium oxide) Color pigment 0 0 4 0 0 4 0 0 4 0 0 4 (cyan)Surfactant 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Styreneacrilic 0 4 2 0 4 2 0 4 2 0 4 2 resin Component 0.1 0 0 0 0 0 0 0 0 0 00 which becomes receiving layer Cationic resin 5 0 0 0 0 0 0 0 0 0 0 01,2-hexane diol 0 3 3 0 3 3 0 3 3 0 3 3 Propylene 20 10 15 20 10 15 2010 15 20 10 15 glycol Water Balance Balance Balance Balance BalanceBalance Balance Balance Balance Balance Balance Balance RecordingLumirror S10 Lumirror S10 Lumirror S10 Lumirror S10 medium Surface Roomtemperature (25° C.) 45° C. Room temperature (25° C.) Room temperature(25° C.) temperature of recording me- dium during recording (heatassist) Volatilization 10% 80% 80% 95% amount of volatile component insecond step Imparting amount 2 14 14 2 14 14 2 14 14 2 14 14 (mg/inch²)Imparting amount 0 1.4 0.56 0 1.4 0.56 0 1.4 0.56 0 1.4 0.56 of colormaterial (mg/inch²) Imparting amount 1.3 0 0 1.3 0 0 1.3 0 0 1.3 0 0 ofcoagulant (× 10⁻⁴ mmol/ inch²) Total imparting 0.102 0 0 0 0 0 0 0 0 0 00 amount of component which becomes receiving layer and cationic resin(mg/inch²) Ratio F  15077:1 15077:1 15077:1 15077:1 Ratio G — — — —Ratio H  13.7:1 — — — Unevenness of A A A A first ink on re- cordingmedium Bleeding when AA AA A B recording first ink and second ink insuper- imposed manner Precipitation of A A A A reaction liquid onrecording medium Cloudiness of A A A A recorded matter Bad odor of A A AA recorded matter Stickiness of A A A A recorded matter Recording speedA A B C Clogging A B A A reliability

TABLE 5 Example 17 Example 18 Example 19 Comparative Example 1 FirstSecond First Second First Second First Second Reaction ink ink Reactionink ink Reaction ink ink Reaction ink ink Ink liquid (white) (color)liquid (white) (color) liquid (white) (color) liquid (white) (color)Magnesium 1.6 0 0 0 0 0 1.6 0 0 0 0 0 sulfate heptahydrate Calcium 0 0 00 0 0 0 0 0 0 0 0 acetate monohydrate Calcium 0 0 0 0 0 0 0 0 0 0 0 0nitrate tetrahydrate Succinic acid 0 0 0 2.3 0 0 0 0 0 0 0 0 Whitepigment 0 0 10 0 10 0 0 10 0 0 10 0 (titanium oxide) Color pigment 0 4 00 0 4 0 0 4 0 0 4 (cyan) Surfactant 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.60.6 0.6 0.6 Styrene acrilic 0 2 4 0 4 2 0 4 2 0 4 2 resin Component 0 00 0 0 0 0 0 0 0 0 0 which becomes receiving layer Cationic resin 0 0 0 00 0 0 0 0 0 0 0 1,2-hexane diol 0 3 3 0 3 3 0 3 3 0 3 3 Propylene 20 1015 20 10 15 20 10 15 20 10 15 glycol Water Balance Balance BalanceBalance Balance Balance Balance Balance Balance Balance Balance BalanceRecording Lumirror S10 NP coating paper Lumirror S10 Lumirror S10 mediumSurface Room temperature (25° C.) Room temperature (25° C.) Roomtemperature (25° C.) Room temperature (25° C.) temperature of recordingme- dium during recording (heat assist) Volatilization 10% 10% 10% 10%amount of volatile component in second step Imparting amount 2 14 14 214 14 2 14 14 2 14 14 (mg/inch²) Imparting amount 0 0.56 1.4 0 1.4 0.560 1.4 0.56 0 1.4 0.56 of color material (mg/inch²) Imparting amount 1.30 0 3.9 0 0 1.3 0 0 0 0 0 of coagulant (× 10⁻⁴ mmol/ inch²) Totalimparting 0 0 0 0 0 0 0 0 0 0 0 0 amount of component which becomesreceiving layer and cationic resin (mg/inch²) Ratio F 15077:1 — 15077:1— Ratio G — 5026:1 — — Ratio H — — — — Unevenness of A A B C first inkon re- cording medium Bleeding when AA A B C recording first ink andsecond ink in super- imposed manner Precipitation of A A C A reactionliquid on recording medium Cloudiness of A A B A recorded matter Badodor of A A A A recorded matter Stickiness of A A A A recorded matterRecording speed A A A A Clogging A A A A reliability Comparative Example2 Comparative Example 3 Comparative Example 4 First Second First SecondFirst Second Reaction ink ink Reaction ink ink Reaction ink ink Inkliquid (white) (color) liquid (white) (color) liquid (white) (color)Magnesium 0 0 0 0 0 0 0 0 0 sulfate heptahydrate Calcium 0 0 0 0 0 0 0 00 acetate monohydrate Calcium 0 0 0 0 0 0 0 0 0 nitrate tetrahydrateSuccinic acid 0 0 0 0 0 0 0 0 0 White pigment 0 10 0 0 10 0 0 10 0(titanium oxide) Color pigment 0 0 4 0 0 4 0 0 4 (cyan) Surfactant 0.60.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Styrene acrilic 0 4 2 0 4 2 0 4 2 resinComponent 0 0 0 5 0 0 0 0 0 which becomes receiving layer Cationic resin0 0 0 5 0 0 0 0 0 1,2-hexane diol 0 3 3 0 3 3 0 3 3 Propylene 20 10 1520 10 15 20 10 15 glycol Water Balance Balance Balance Balance BalanceBalance Balance Balance Balance Recording Lumirror S10 Lumirror S10Lumirror S10 medium Surface 45° C. Room temperature (25° C.) 70° C.temperature of recording me- dium during recording (heat assist)Volatilization 80% 10% 95% amount of volatile component in second stepImparting amount 2 14 14 2 14 14 2 14 14 (mg/inch²) Imparting amount 01.4 0.56 0 1.4 0.56 0 1.4 0.56 of color material (mg/inch²) Impartingamount 0 0 0 0 0 0 0 0 0 of coagulant (× 10⁻⁴ mmol/ inch²) Totalimparting 0 0 0 0.2 0 0 0 0 0 amount of component which becomesreceiving layer and cationic resin (mg/inch²) Ratio F — — — Ratio G — —— Ratio H — 7:1 — Unevenness of C C A first ink on re- cording mediumBleeding when C C B recording first ink and second ink in super- imposedmanner Precipitation of A A A reaction liquid on recording mediumCloudiness of A A A recorded matter Bad odor of A A A recorded matterStickiness of A A A recorded matter Recording speed A A B Clogging B A Creliability

By comparing Examples and Comparative Examples 1 to 3, it was found thatthe ink sets in which the reaction liquid does not contain the coagulantare inferior to the effect of suppressing the bleeding of the secondink. In addition, by comparing Examples and Comparative Example 4, itwas found that when the reaction liquid does not contain the coagulant,while the effect of suppressing the bleeding of the second ink wasimproved by heating the recording medium to a temperature of 70° C., theclogging reliability deteriorated.

It was found that the amount of the polyvalent metal salt used wasincreased and the bleeding was suppressed from Examples 1 to 4. Inaddition, it was found that the precipitation of the reaction liquid orthe cloudiness of the recorded matter on the recording medium weresuppressed as the amount of the polyvalent metal salt used is small. Inaddition, Examples 5 to 11 show that there is a similar tendency evenwhen using other polyvalent metal salts or organic acids.

Furthermore, from Examples 12 and 13, it was found that the bleeding wasfurther suppressed using the component which becomes the receivinglayer, and the cationic resin. In addition, by comparing Example 14 andother Examples, and Comparative Examples 2 and 4, it was found that thelower the heat assist temperature is, the more excellent the cloggingreliability is. In addition, from Examples 2 and 14 to 16, it was foundthat the bleeding was suppressed if the volatilization amount is not toolarge while there was a tendency that the bleeding was suppressed if thevolatilization amount of the volatile component is large. It is inferredthat when the volatilization amount is too large, the coagulantcontained in the reaction liquid cannot be sufficiently mixed on thefirst ink and it is difficult to react the second ink and the coagulant.In addition, it was found that the lower the volatilization amount is,the more excellent the recording speed and the clogging reliability are.

Example 17 shows that the invention was effective even if the white andthe color of the first ink and the second ink were converted to eachother. In addition, Examples 9 and 18 show that the invention waseffective even if other recording media were used. It was found that thebleeding tends to be further improved when using the low-absorptiverecording medium, but in contrast, the invention is more effective whenusing the non-absorptive recording medium since it is more excellent inthe water resistance and the friction resistance. Furthermore, bycomparing Example 19 and other Examples, it was found that as thecontent of the surfactant of the reaction liquid was large and thesurface tension was low, the bleeding, the precipitation of the reactionliquid on the recording medium, or the cloudiness of the recorded matterwas suppressed.

Although the recording was performed using the serial printer in theabove-described example, it is also possible to perform the recordingusing the line printer as shown in FIGURE. In this case, it is possibleto suppress the volatilization amount of the recording medium byadjusting the time between the imparting of the reaction liquid and thefirst ink through a reaction liquid imparting head and a first inkimparting head and the imparting of the second ink after the recordingmedium is transported to the position facing a second ink head, usingthe speed of transporting the recording medium, or the like.

What is claimed is:
 1. A recording method, comprising: providing an inkset including a reaction liquid containing coagulant, a first inkcontaining a first color material, and a second ink containing a secondcolor material; imparting the reaction liquid of the ink set to anon-absorptive recording medium or a low-absorptive recording medium;imparting the first ink of the ink set to the area to which the reactionliquid is imparted; and imparting the second ink of the ink set to thearea to which the first ink is imparted, wherein, before the impartingof the second ink, the reaction liquid and the first ink that are eachimparted to the recording medium are heated, a surface tension of thereaction liquid is less than or equal to 35 mN/m at a temperature of 25°C., a surface temperature of the recording medium is lower than or equalto 50° C. in the heating of the reaction liquid and the first ink thatare each imparted to the recording medium before the imparting of thesecond ink, and one of the first ink and the second ink is a white inkcontaining a white color material as the first color material or ametallic ink containing a metallic color material as the first colormaterial, and the other of the first ink and the second ink is a yellowink, a magenta ink, or a cyan ink containing the second color materialor a black ink containing a black color material as the second colormaterial.
 2. The recording method according to claim 1, wherein thecoagulant contains at least one selected from a group consisting of apolyvalent metal salt and an organic acid.
 3. The recording methodaccording to claim 1, wherein a surface tension of the reaction liquidis greater than or equal to 1 and less than or equal to 35 mN/m at atemperature of 25° C.
 4. The recording method according to claim 1,wherein the reaction liquid further contains at least one selected froma group consisting of a component which becomes a receiving layer of anink applied after the reaction liquid, and a cationic resin.
 5. Therecording method according to claim 4, wherein a mass ratio of at leastone (unit: g) selected from the group consisting of the component whichbecomes the receiving layer, and the cationic resin, which are containedin the reaction liquid, to the first color material (unit: g) containedin the first ink is 7:1 to 70:1 (the first color material: at least oneselected from the group).
 6. The recording method according to claim 1,wherein a content of the first color material in the first ink withrespect to a total mass of ink is 10 to 15 mass %; and a content of thesecond color material in the second ink with respect to the total massof the ink is 2 to 4 mass %.
 7. The recording method according to claim1, wherein the first ink and the second ink each contain a resinemulsion.
 8. The recording method according to claim 7, wherein theresin emulsion contains at least one of a urethane resin, a(meth)acrylic-based resin, and a styrene-(meth)acrylic-acidcopolymer-based resin.
 9. The recording method according to claim 1,wherein at least a portion of the reaction liquid and the first inkwhich are imparted to the recording medium are dried by the heating. 10.The recording method according to claim 1, wherein the surfacetemperature of the recording medium is less than or equal to 45 degreesC. when the reaction liquid and the first ink that are each imparted tothe recording medium are heated before the imparting of the second ink.11. The recording method according to claim 1, wherein 10 mg/inch² orless of the reaction liquid is imparted to the recording medium.
 12. Therecording method according to claim 1, wherein 5 to 20 mg/inch² of thefirst ink is imparted to the recording medium, and 5 to 20 mg/inch² ofthe second ink is imparted to the recording medium.
 13. The recordingmethod according to claim 1, wherein a total amount of the first andsecond color materials contained in the first ink and the second inkimparted to the recording medium is 0.5 to 3 mg/inch².
 14. The recordingmethod according to claim 1, wherein the first ink, the second ink, andthe reaction liquid are each water-based.
 15. The recording methodaccording to claim 1, wherein the reaction liquid contains a surfactant.16. The recording method according to claim 1, wherein the reactionliquid contains a surfactant, and a content of the surfactant is 0.6mass % or more with respect to a total mass of the reaction liquid. 17.The recording method according to claim 1, wherein a content of a resinof a resin emulsion contained in the first ink is 3 mass % or more withrespect to a total mass of the first ink.
 18. The recording methodaccording to claim 1, wherein a content of a resin of a resin emulsioncontained in the second ink is 3 mass % or more with respect to a totalmass of the second ink.
 19. A recording apparatus that performsrecording by the recording method according to claim 1.